Electronic keyboard systems are known wherein keys are moveably positioned on a given surface such as a surface of a remote control device or computer input keyboard. In operation, depression of a key by a user closes a contact thereby making an electrical connection that uniquely identifies the key that was pressed. The unique identifier is transmitted by wire or wirelessly to a corresponding device that typically performs some action that corresponds to the particular key that was depressed.
In construction, an x-y coordinate grid or matrix of conductive paths is typically deposed on a bottom portion of the keyboard. Positioned above each of the conductive paths is a contact pad. When the key is not depressed, the contact pad is positioned so as not to be in electrical contact with an underlying conductive path. When the key is depressed, the contact pad comes into electrical contact with two ends of an underlying conductive path, thereby closing the circuit and providing the unique identifier determined by the X,Y coordinate of the depressed key as discussed above.
U.S. Pat. No. 4,005,293 (“the '293 Patent”) shows such a keyboard and is incorporated herein as if set out in its entirety. The '293 Patent utilizes a circular contact area on the contact pad.
The keys generally operate well when depressed from a center of the key but have problems in that keys may be depressed in numerous ways, such as an off-center depression, which may not result in a proper connection with the underlying grid. In this case, the unique identifier may not toe produced, and therefore, the intended operation of the keyboard may fail.
FIG. 1 shows a prior art solution wherein the conductive paths of the '293 Patent are replaced with a conductive tracing 100 that has a conductive paths 110, 112 with a conductively isolating area 114 in the form of a diminishing sinusoidal wave. It has been found that the conductive tracing 100 performs well in some off-center depressions. However, the conductive tracing 100 still has dead zones as indicated by dashed lines 120. These dead zones are problematic when the key is depressed, for example, in an area along an outside periphery of a corresponding key.
It is an object of the present system to overcome disadvantages and/or make improvements in the prior art.